1. Field of the Invention
The present invention relates to an inspection apparatus for inspecting a microarray, particularly to an inspection apparatus for examining a DNA microarray with an area sensor like CCD.
2. Description of the Related Art
The area sensor employed conventionally with such an inspection apparatus includes CCD sensors, and CMOS sensors. Such a sensor reads signal charges stored in photodiodes, photoelectric conversion elements for picture elements, as image information. Japanese Patent Application Laid-Open No. 2005-181145 discloses a nucleic acid analysis apparatus which reads fluorescence of a DNA microarray with a CCD sensor. This apparatus excites probes in a DNA microarray by irradiation with a light-emitting diode and detects the fluorescence of the respective probes with a CCD sensor. This apparatus is capable of measuring simultaneously the fluorescence intensities of the respective probes of a DNA microarray under nearly uniform measurement conditions at a higher precision. Moreover, the reading unit of the apparatus occupies a smaller space, being less expensive, causing less failure, and being nearly maintenance-free.
The area sensor like the CCD can contain some defective picture elements owing to a defect of the photodiode. The defective picture element will disturb normal reading of the signal charge information. In the case where a fluorescence image formed by hybridization of probes of a DNA microarray is picked up, the defective picture element overlapping the spot image of the probe disturbs the normal detection of the fluorescence intensity.